Apparatus for the control of highway crossing signals



A. R. WHITEHORN APPARATUS FOR THE" CONTROL OF HIGHWAY CROSSING SIGNALSpril 8, 1941.

Filed April 7. 1939 INVENTOR.

7 7 yfdaiw Patented Apr. 8, 1941 APPARATUS FOR THE CONTROL OF HIGH- 1WAY CROSSING SIGNALS Arthur R. Whitehorn, Downers Grove, Ill., assignorto Western Railroad Supply Company, Chicago, 111., a corporation ofIllinois Application April 7, 1939, Serial No. 266,549

14 Claims.

The present invention relates to railroad warning signals in general andparticularly to a signalling system designed to accommodate high speedand slow speed trains without variation in the warning period precedingthe arrival of the train at a highway crossing. More specifically theinvention comprises a signal-operating system for railroad-highwaycrossings in which a short speed-gauging section is used with completeaccuracy and in which variations in the operating mechanismscharacteristics due to variable operating conditions have beeneliminated.

It is an object of the present invention to provide a new and improvedtrain actuated railroadhighway grade crossing signal control system.Another object of the invention is to provide a crossing signaloperating system for railroads in whichthe passage of a train thru ashort track section gauges the train speed and causes the signals to beoperated with trains at varying distances from. the crossing dependingupon the train speed so that the signal is always operated for apredetermined time period before the train arrives at the crossing.Still a further object of the invention is to'provide a signal-operatingsystem in which the operating characteristics of the timing mechanismare fixed and in which no delay for motor starting or acceleration ispresent. Another object of the invention is to provide a crossing signaloperating system, in which the windup and rundown operations are gravityactuated. These and other more specific objects of the invention willappear upon reading the following specification and claims and! uponconsidering in connection therewith the attached drawing.

Referring now to the drawing in which apreferred embodiment of thepresent invention is disclosed Figure l is a diagrammatic illustrationof the system comprising the present invention in the track-clearcondition; and FigureZ is a diagrammatic illustration; of the electricalcircuits only of thepresentinvention.

Automatic crossing signalsai'e of course quite old and well known buttheincrease in the operating speeds oftrains has presented a problem notpreviously present. It is recognized as being desirable to cause thesignal at a highway crossing to be put into operation a fixed periodbefore the arrival of the train at the crossing. With 1 systems in whichthesignal is operated as the train reaches a fixed point spaced from thecrossings it is clear that fast trains will reach the crossing in lessertimes than slower trains. With train speeds ranging up to 120 m. p. h.the time variations in the systems described is so great as to beobjectionable. If such systems are designed to give an adequate warningperiod for high speed trains then the period for slow speed trainsbecomes so great as to be unreasonable.

Heretofore systems have been presented which attempted! to gauge thespeed of the train and vary the signal operation in accordancetherewith. Such systems have had. certain fundamental objections. Theyhave used long sections in which to gauge the train speed and cause thetrack sections used by the signal to be so long that speed variationsaffect the operating characteristics. Such systems are objectionablebecause of the excessive costs of installation caused by the longelectrical circuits. Systems heretofore proposed to accommodate highspeed trains have been objectionable in that varying operatingcharacteristics in electrical driving units, whether occasioned byvoltage or temperature changes, or however, have caused variations inthe operation of the timing mechanism. Such variations increase inimportance with the decrease in the length of the initial track sectionin which the train speed is gauged.

In the system constructed in accordance with the present invention it ispossible to use a short track section for gauging the train speed andthe windup of the timing mechanism, for gravity is used in both thewindup and rundown operations, an electrical motor being called upon torestore the system to the track-clear condition after the train haspassed.

Referring again to the drawing, and to Figure 1 in particular, apreferred embodiment of the invention is illustrated. A railroad trackis seen to approach a highway and to be divided into mutually insulatedsections AB, BC and C--D; the highway crossing the tracks adjacent pointD. Each track section is energized by a battery, indicated at I, 2 and 3and across the rails of each section is a relay coil, indicated at 4, 5and 6. Relays 4, 5 and 6 are normally energized by the batteries l, 2and 3, respectively, and each is adapted. to be shunted by the entranceof a train into its track section.

Relay 4, in section A-B, is provided with a pair of movable contacts 4Aand 4C. With the track clear and the relay energized contact 4A seats onstationary contact 43 but with the relay shunted 4A and 4B open andcontact 40 drops onto stationary contact 4D.

Relay 5 in section BC is also provided with a pair of movable contacts5A and 50 which normally seat on stationary contacts 53 and 5D, re-

spectively, with the relay energized, but which drop therefrom with therelay shunted by a train entering section BC. Contact A drops intocontact with a second stationary contact 5F.

Relay 6 in section C-D has a single movable contact 6A which normallyengages stationary contact 513, the contacts opening with the relayshunted.

A final relay 1, the current to which all the re mainder of the systemis intended to control, is provided with a movable contact 1A and astationary contact TB which are connected in series with and control theflow of current to the highway signal 8.

The timing mechanism now to be described, and indicated generally at H],is controlled by the relays 4, 5 and 6 and their contacts which in turnare controlled by the passage of a train thru the track section in whichthey are connected.

The timing mechanism comprises first a relatively large weight Msuspended by suitable means, such as a rope, cord, cable or chain l2,from a pulley l3 mounted on a rotatable shaft M. In the track-clearcondition illustrated in the drawing the weight M is in its uppermostposition and the cord I2 is wound around the pulley I3. The weightnormally cannot move downwardly by rotating the shaft for a ratchetwheel l5 on the shaft M is locked by a pawl l6 which is held in place byan energized solenoid When the ratchet 5 is released to permit the shaftM to rotate and the weight I to move downwardly under the force ofgravity the weight moves and the shaft rotates at a constant speed, agear 4| on the shaft cooperating with an escapement 42 to effect thisresult.

A second weight is suspended from a second shaft 2i which is connectedto the shaft |4 thru an electromagnetic clutch 22 which includes clutchdiscs and a stationary normally unenergized winding 23. As in the caseof weight M weight 23, which is the smaller, is connected to itssupporting shaft by suitable means such as a rope 24 which winds arounda pulley or spiral drum 25 having a definite contour such that thedistance traveled by the weight 20 is related to the rotation of theshaft 2| in a predetermined manner, as will be hereinafter explained.Guide l8 restrict the weight to vertical movement.

Carried by the weight 20 and movable vertically therewith is a toothedrack 26. A gear 21 carried by a shaft 28 meshes with the teeth of therack and is rotated by the rack movement. A second gear 29 adjacent gear21 On the shaft 28 cooperates with an escapement 30, of a well knowntype, to restrict gear 29 to a constant speed, although interruptednecessarily, of rotation. As gear 2'! is keyed to gear 29 by aspring-pressed ratchet 34 with the gear 21 rotated by the downwardtravel of rack 25, it is seen that the rack and the weight 20 willdescend at a constant rate. During the ascent of the weight, however,the direction of rotation of gear 21 is such that ratchet 34 does notengage the teeth of gear 29.

In their vertical movement the weights and 20 function to operatecertain contacts for reasons to be explained, Weight upon reaching theupper limit of its travel abuts the insulated end of movable contact 3|A of switch 3| to move it to open position relative to stationarycontact 3|B. Weight 20 upon moving from its lowermost position permitsspring-biased switch 32 to open and close spring-biased switch 33 thrumoving from contact with the insulated ends of movable contacts 32A and33A, respectively, which then move to their biased positions relative tostationary contacts 32B and 33B, respectively.

An electric motor M is provided to wind up the weight II and isconnected to the shaft M by a worm gear 36 on a shaft which meshes withgear teeth formed on the gear-pulley I3. Shaft 35 is aligned with theshaft 3! of the mo tor M and is adapted to be connected thereto by anormally unenergized electro-magnetic clutch 38 having a winding 39 andclutch discs. The winding 39 is in the circuit of the motor M and isenergized only when the motor is energized. The clutch being normallyopen the downward movement of the weight M does not rotate the motor. Abattery B is provided to drive the motor, the current to which iscontrolled by two switches 3| and 32 which are in series and arepositioned by the weights H and 20, respectively.

The operation of the ystem constructed in accordance with the presentinvention is as follows, reference being had to both figures of thedrawing in which, it is to be remembered, the condition illustrated isthe track-clear condition. The condition of the system will now bedescribed for various positions of the train.

Track clear condition In this condition the train has not yet enteredthe track from A to D and the parts are as related in the drawing. Allthe track relays 4, 5 and 6 are energized a is the signal-controllingrelay 1. The weight M is in its upper position where it is held by thepawl 5 which cooperates with the ratchet l5 to prevent the rotation ofshaft M. The winding H of the pawl I5 is en ergized thru contacts 4A and4B. The weight 20 is in its lowermost or rundown position. The motorcircuit is unenergized, the switch 3| being held open by the weight M.

Train enters section A-B A train enters section A-B moving in thedirection of the highway crossing, Relay 4 is de-energized and contact4A separates from 4B. Winding I! of the pawl I6 is thereuoon deenergizedand the latter element moves from its locking engagement with ratchet 5.Contacts 40 and 4D close and thereby energize winding 23 of the magneticclutch 22 and causing that element to connect shafts l4 and 2|.Instantaneously the .weight begins its downward movement and drives theshaft l4 thru the pulley |3, the shaft 2| being connected to shaft l4thru clutch 22, also rotates. The motor M does not rotate for the clutch38 is open. The weight M is much heavier than weight 20 and causes thatmember to be lifted and WOllIld. upon its camshaped pulley 25, theshafts l4 and 21 rotating at the maximum speed permitted by theescapement 42 which contacts the gear 4|.

The downward movement of weight M caused switch 3| to close so thatcurrent from battery B would have energized motor M and clutch winding39 had not the simultaneous upward movement of weight 20 opened switch32 which is also in series with switch 3|. The upward movement of weight20 also caused switch 33 to close thereby completing a shunt aroundcontacts 5C and 5D'in the circuit of relay 7 so that the de-energizationof relay 5, upon the train entering section BC, will not cause releaseoperation of relay 1.

During the presence of the train in section A-B, and until it enterssection BC, the weight I will continue to fall and the weight 20 to movevertically upward, the weight-supporting rope 24 being wound around thecam pulley 25 which is shaped in a definite manner so as to displace theweight 2|] a predetermined distance such that the time (rundown)required for it to return to its initial position at a constant speedwill bear a predetermined relationship to the timerequired to lift it(windup). With the shaft 2| rotating at a constant speed under thecontrol of escapement 42 it is clear that the displacement of the weight20 will be controlled directly by the shape of cam 25'. The escapement30 is, of course, inoperative in this windup period. The surface of thepulley is so shaped relative to the center of shaft rotation that at anygiven height to which the weight 20 has been lifted by the pulley 25,its time of descent at a constant speed and under its own gravitationalforce will bear a fixed relationship to the time of its ascent. If Tex:rundown time; TAB=time required for front of train to pass thru sectionA-B and so equals the windup time; AB and BD=lengths of section. AB andBB in the same units of measurements; and K221. constant in secondsequal to the period of signal operation before the train reaches thehighway, then the formula gives the relationship of the period of windupto the period of rundown. The spiral drum 25 is so contoured that whenTAB is the Windup time TBx as indicated by the formula will be therundown time.

Train enters section B-C' The forward end of the train passes fromsection A--B into section B--C. Relay is immediately de-energized;contacts 5A, 5B and 5C, 51) open while 5A, 5F close. The closing ofcontacts 5A, 5F throws a shunt around open contacts 4A,

the reverse direction under the torque exerted by the weight 2|] thruits cam-pulley 25.

The opening of contacts 50, 5D had no effect for the initial upwardmovement of weight 20 caused switch 33 to close to effect a shuntthere'- around, as described supra.

During the descent of weight 20 the circuit condition remains asdescribed. The weight, traveling downwardly under gravity at a constantspeed controlled by the escapement 30, arrives at its lowermost positionin the time Tex set forth above which time is a period K before thearrival of the train at the point D. As this is the time it is desiredthat the signal be placed in operation this result is effected by theopening of the contacts 33A, 33B of the switch 33 by the weight. Currentis thereby cut off from the relay I which upon being de-energized causesits contacts 1A, TB to open whereupon current ceases to flow to thesignal a which is thereupon placed into operation. It is to beunderstood that the signal 8 is of any common and well known type.

Train enters section CD The section CD is only a safety section. It isintended that the signal shall be operated normally before the trainreaches 0. Should there be a failure for any reason so that the signalhas not been operated by the time the train reaches C the entrance ofthe train into section CD causes immediate operation. The contacts 6Aand 6B of relay 6 of section CD are in series with the relay 1 and uponrelay 6 being shunted by the entrance of the train in section CD thecontacts 6A, 63 open and relay I is de-energized with resulting signaloperation, as above set forth.

The re-setting of the mechanism To place the system in condition for thearrival of a subsequent train it is necessary to lift the large weight Mto its initial or waiting position. To accomplish this function there ispro vided, as described, a motor M connected in series with a battery B.and a switch 3| and a switch 32. The contacts 3IA, 3| B of switch 3| arebiased to a closed position except when held open by the weight 2'0 inits upper position, a condition which does not exist subsequent to thepassing of a train. The contacts 32A, 32B of switch 32 are normallybiased open but are held closed by the weight 20 in its lower or waitingposition.

The weight 2|] having arrived at its lowermost position and the signaloperated for the passing train the closing of the switch 32 causes theflow of current to the motor M and to the winding 39 of clutch 38 whichis in series therewith. The clutch is closed and motor shaft 31 isconnected to shaft 35 and the instantaneous rotation of the motor causesthe gear 36 to rotate gear-pulley l3 to wind up the weight I to itsoriginal position. The motor is de-energized by theweight opening theswitch 3| at the top of its travel, the winding 39 being alsotie-energized. The downward movement of the weight is again prevented bythe pawl |6, the winding ll of which has been energized by the closingof contacts 4A, 43 upon the train passing from section A--B.

The formula which is used above is arrived by the following reasoning. v

Regardless of the train speed it is desired that the signal begin itsoperation a predetermined period before the train reaches the highway.This warning period is a constant which may be called K and can betaken, for example, to be 20 seconds. Referring to Figure 1 the dottedline X-X is a variable position on the track between B and D at whichthe train is positioned when the signal begins operation. Let Tex be thetime required to travel thedistance B to X for any particular train.Obviously for a fast train X will befarther from D than for a slow trainfor both are to reach the crossing during the same elapsed period fromposition X. Itis clear that if the signal can be put into operation foreach particular train when it reaches its X position that thedesiredresult will accrue. It has been calculated that for any giventrain Where the constant K is decided upon and the distances A-B and BDknown, itis olearthat Tex can be calculated by substituting in theformula the value of TAB- Of course TAB is the time required by thetrain to travel the distance A--B,- etc. As the range of train speeds isknown the calculation can be done by assuming values of TAB. It is ofcourse obvious that the proper units must be used, for example, K, TABand Tex in seconds and BD and AB in feet.

The formula is derived in the following manner:

The advantages of the present system are many but its ability to actinstantly under all conditions, together with its inherent use of ashort initial track section, made possible by the instantaneousoperation, are not the least.

I claim:

1. In a railroad-highway signal control system a plurality of mutuallyinsulated track sections including a measuring and an operating sectionapproaching a highway, a signal at the highway, a normally energizedrelay in each of said sections adapted to be shunted by the entrance ofa train into the section in which it is connected, and means responsiveto the passage of a train through said sectionsto cause the operation ofthe signal at a predetermined constant time interval prior to thearrival of the train at the highway; said means comprising an element,gravity actuated means controlled by the relay in the measuring sectionto operate said element, a member displaceable at a variable rate bysaid element, means to release said member to return by gravity to itsinitial position controlled by the relay in the operating section, meansto eiTect a constant speed return of said member, and motor-operatedmeans to return said system to its initial condition, and means toenergize said last-mentioned means upon the train passing the highwayand the cessation of the operation of the signal.

2. In a railroad-highway signal control system, a plurality of mutuallyinsulated track sections approaching a highway, a signal at the highway,a normally energized relay in each of said sections adapted to beshunted by the entrance of a train into the section in which it isconnected, and means responsive to the passage of a train thru saidsections to cause the operation of the signal at a predetermined timeinterval prior to the arrival of the train at the highway; said meanscomprising a statically energized energy-storing unit adapted to expendenergy during a time interval required for a train to travel one of saidtrack sections and controlled by the relay in that section, deenergizedenergy-storing unit adapted to receive energy from the loaded unitduring the said time interval and to expend it upon the shunting of therelay in a second section nearer the highway at a different ratethereafter, means to place the signal into operation upon the release ofthe energy stored in said unloaded unit, and electrical means to reloadsaid statically energized energy-storing unit.

3. In combination, a railway track intersected by a highway, a signal atthe intersection, and signal-controlling means to operate the signal ata predetermined constant time period prior to the arrival of trainstraveling at varying speeds at the intersection; said signal-controllingmeans comprising an element normally occupying a raised position andadapted to fall by gravity when released, means to release said elementto fall by gravity during the time interval required for an approachingtrain to travel a fixed distance on said track spaced from saidintersection, a second element normally occupying a lower position,means to connect said second element to said first element to be raisedthereby at a varying rate during the fall of said first element, meansto release said connecting means upon said train reaching a fixed pointafter leaving said fixed distance, means to maintain a constant returnspeed in said second element, and means effective when said secondelement has reached a predetermined position to place said signal inoperation.

4. In combination, a railway track intersected by a highway, a signal atthe intersection, and signal-controlling means to operate the signal ata predetermined constant time period prior to the arival of trainstraveling at various speeds at the intersection; said signal-controllingmeans comprising a first weight positioned to fall by gravity and asecond weight positioned to be raised against gravity, means to releasesaid first Weight to fall by gravity during a time interval required forany train approaching the highway to travel a predetermined fixeddistance, means actuated by the movement of said first weight to liftsaid second weight at a varying rate, means to release said secondweight at the end of said time interval to fall by gravity, means tomaintain a constant rate of fall in said second weight, and meansefiective when said second weight has fallen to a predetermined positionfor placing said signal in operation.

5. In combination, a railway track intersected by a highway, a signal atthe intersection, and signal-controlling means to operate the signal ata predetermined constant time period prior to the arrival of trainstraveling at various speeds at the intersection; said signal-controllingmeans comprising; a movable element, means effective upon said elementreturning to a predetermined position for placing the signal inoperation, traincontrolled gravity-operated means to raise said elementfrom said position at an increasing rate during the period required fora train approaching the crossing to travel a predetermined distancespaced therefrom, and means to return said element under gravity towardsaid position upon said train reaching a predetermined point and at arate having a predetermined relationship to the rate of originalmovement.

6. In combination, a railway track intersected by a highway, a signal atthe intersection, and signal-controlling means to operate the signal ata predetermined constant time period prior to the arrival of trainstraveling at various speeds at the intersection; said signal-controllingmeans comprising: a movable weight, means effective upon said elementfalling to a predetermined lower position for placing the signal inoperation, train-controlled gravity-operated means to raise said weightfrom said position at a varying rate during the period required for atrain on said track approaching the crossing'to travel a predeterminedfixed distance spaced therefrom, and means to effect the constant speedreturn of a said weight toward said position upon said train reaching apredetermined point. i

'7. In combination, a railway track intersected by a highway, a signalat the intersection, and a railroad-highway signal control system tooperate said signal and including a first weight normally biased to fallby gravity, means to maintain a constant speed of fall of said weight, asecond weight, means to raise said second weight at a varying rate uponthe fall of said first weight, train-controlled means to release saidfirst weight to fall during the time interval required for a train onsaid track approaching a highway crossing to cover a fixed distancespaced therefrom, train-controlled means to release said second weightto fall at the termination of the said time interval, means to restrictsaid second weight to a constant rate of fall, and means efiective whensaid second weight has fallen to a predetermined position for placingsaid signal in operation.

8. In combination, a railway track having sections and intersected by ahighway, a signal at the intersection, and a railroad-highway signalcontrol system to operate said signal and including means to place thesystem in operation upon a train entering a track section comprising agravity actuated windup mechanism operative during the time required fora train approaching the intersection to traverse one of said sections,

a displaceable element movable by said windup the operation of a signalupon the return movement of said displacement element to a predeterminedposition, and means to return said wind up mechanism to initialcondition.

9. In combination, a railway track intersected by a highway, a signal atthe intersection, and signal-controlling means to operate the signal ata predetermined fixed time period prior to the arrival of trainstraveling at'various speeds at the intersection; said signal-controllingmeans comprising a first weight, normally energized means holding saidfirst weight in an upper position, means to tie-energize said holdingmeans upon a train approaching the highway, means to effect a constantspeed movement of said weight under the influence of gravity, a secondweight, normally unenergized clutch means to connect said second weightto said first Weight upon a train approaching a highway, means to raisesaid second weight at a varying rate upon the movement of said firstweight under gravity, means to de-energize said clutch means todisconnect said second weight from said first weight after the train hastraveled a predetermined fixed distance from its position at the time ofthe release of said first weight, means to effect a constant speedreturn of said second weight to its initial position, and meanseffective when said weight has reached its initial position for placingsaid signal in operation.

10. In combination, a railway track intersected by a highway, a signalat the intersection, and signal-controlling means to operate the signalat a predetermined fixed time period prior to the arrival of trainstraveling at various speeds at the intersection; said signal-controllingmeans comprising a first weight, normally energized means holding saidfirst weight in an upper position, means to de-energize said holdingmeans upon a train approaching the highway, means to effect a constantspeed movement of said weight under the influence of gravity, a secondweight, normally unenergized clutch means to connect said second weightto said first weight upon a train approaching a highway, means to raisesaid second weight, at a varying rate upon the movement of said firstweight under gravity, means to deenergize said clutch means todisconnect said second weight from said first weight after the train hastraveled a predetermined fixed distance from its position at the time ofthe release of said first weight, means to effect a constant speedreturn of said second weight to its initial position, means effectivewhen said weight has reached its initial position for placing said signal in operation, an electric motor to return said first weight to itsinitial position, normally unenergized clutch means to connect saidmotor to said first weight, and means to energize said clutch to connectsaid motor to said first weight and to energize said motor to raise saidfirst weight upon said signal being placed in operation.

11. In a railroad-highway signal control system, a plurality of mutuallyinsulated track sec tions approaching a highway, a signal at thehighway, a normally energized relay in each of said sections adap-tedtobe shunted by the entrance of a train into the section in which it isconnected, and means responsive to the passage of trains traveling atvarious speeds thru said sections to cause the operation of the signalat a predetermined fixed time interval prior to the arrival of the trainat the highway; said means comprising a first weight unit including agravity actuated weight, means holding said first weight againstgravity, a motor to lift said weight, and electrical clutch means toconnect said motor to said first weight; and a second weight unitincluding a gravity actuated weight, means to lift said weight at avariable rate, means to effect a constant speed descent of said weightunder the action of gravity; means to actuate the weight holding meansof the first weight unit to release said weight to fall by gravity upona train entering a first track section and controlled by the relay ofthat section, means to clutch said first weight to the weight liftingmeans of the second weight unit with said train in said section andcontrolled by the relay of that section to cause said second weight tobe lifted, said means to clutch also being controlled bythe relay of anadjacent second track section and adapted to declutch said first weightfrom said second weight unit upon the train entering the second sectionto release said second weight, and means effective upon the return ofsaid second weight to its initial position for placing said signal inoperation.

12. The construction defined in claim 11 characterized in that means areprovided to clutch said motor to said first Weight and to energize itupon the return of said second Weight to its initial position.

13. The construction defined in claim 11 characterized in that means areprovided in said first weight unit to effect a constant speed movementthereof under the actuation of gravity.

14. In a railroad-highway signal control sys tem, a plurality ofmutually insulated track sections approaching a highway, a signal at thehighway, a normally energized relay in each of said sections adapted tobe shunted by the entrance of a train into the section in which it isconnected, and means responsive to the passage of a train thru saidsections to cause the operation of the signal at a predetermined timeinterval prior to the arrival of the train at the highway; said meanscomprising a statically energized energystoring unit adapted to expendenergy dynamically during a time interval required for a train to travelone of said track sections and controlled by the relay in that section,a deenergized en- 10 ergy-storing unit adapted to receive energy fromthe energized unit during the said time interval and to expend it at adifferent rate thereafter, said ole-energized unit being controlled bythe relay in a second track section between the first section and thehighway, and means to place the signal into operation upon theexpenditure of the energy stored in said unloaded unit.

ARTHUR R. WHITEHORN.

